Good sensory feel, i.e., softness and smoothness, is a necessity for both leave-on and rinse off types of personal care products, including face care products, body care products, hand care products, hair care products, sunscreens, antiperspirants, deodorants, color cosmetics, and face/hand/body wash. Many sensory enhancers have been developed to address this need, such as cationic surfactants (which are cationic compounds with quaternary ammonium functional groups, also known as “cationic quats”) and silicone oils (which are typically polysiloxanes with organic side chains). Cationic quats and silicone oils are commonly used in skin care formulations to improve their sensory feel characteristics. However, high levels of cationic quats cause irritation on skin and silicone oils don't provide sufficient sensory benefits to satisfy consumer needs.
Silicone elastomers were developed as alternatives to cationic quats and silicone oils and are currently considered one of the best sensory modifiers used in skin care formulations. Due to the unique structure of silicone elastomers (i.e., loose-crosslinked silicone polymer swollen in silicone oil) and large particle size, it has a skin feel unlike any of the silicone fluids or cationic quats. Their feel has been described as “velvety”, “powdery”, “smooth,” and “cushion feel”. Also, their skin feel can be modified by controlling the amount of solvent in the formula, and therefore the degree of swelling. In general, the irregular shapes of these soft elastomer particles give a distinctly different feel on the skin.
The major drawbacks of silicone elastomers, however, are high cost and limited compatibility with other solvents. As a result, silicone elastomers tend to be limited high end skincare products, with the aforesaid shortcomings prohibiting their broad application for the mass market. There is also a contemporary trend toward reducing the use of silicones due to unwanted build-up on treated surfaces and environmental persistence. The absence of technology for producing new materials and formulations with performance comparable to silicone oils limits entry of new personal care products into high-volume and high demand personal care markets.
Nonetheless, efforts continue to develop alternatives to the silicone elastomers for achieving soft feel in personal care products. For example, U.S. Pat. No. 6,471,952 discloses cosmetic and dermatological compositions for treating keratinous material (i.e., hair) comprising at least one grafted silicone polymer and at least one combination of an anioinic polymer and a cationic polymer. The grafted silicone polymer contains a polysiloxane portion and a non-silicone organic chain portion, wherein either may be the main chain with the other grafted thereon. The polysiloxane portion may, for example, be derived from vinyl silicone macromers or polymers, and the non-silicone organic chain may, for example, be derived from monomers having at least one ethylenic unsaturation, such as acrylic acid, methacrylaic acid, N,N-dimethylacrylamide, maleic acid, maleic anhydride, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, vinylpyrrolidone, acrylic or methacrylic acid esters of C1-C18 alcohols, styrenes, vinyl acetate, alkyl methacrylates, among others. Compositions containing such grafted silicone polymers provide excellent hair care and styling products which impart good sensory feel and softness to the hair.
International Patent Application Publication WO2004/065430 discusses the preparation of surface active compounds comprising polyolefin succinic anhydride compounds of low color and their use in various applications including personal care products, coatings, and light colored lubricants and fuels. The polyolefin succinic anhydride compounds are the product of reacting a polyolefin, preferably with at least 75 mole % derived from isobutylene and at least 45 mole % having a terminal vinylidene group, with maleic anhydride or fumaric acid, or esterification products of either with C1-8 or C10 alcohols. These polyolefin succinic anhydride compounds were found to impart a very desirable feel to human skin when applied in an oil or water-based personal care formulations such as skin lotions and soaps, hair shampoos and conditioners, shave creams and gels, facial products and cosmetics.
International Patent Application Publication WO2011034836A1 describes a class of silane containing polyolefins, for example, polyethylenes grafted with vinyl(polyalkoxy)silane monomers (i.e., vinyltrimethoxysilane) which are suitable for forming melt-shaped articles such as components for wires and cables. Upon curing, these compounds produce a stable thermoplastic compositions having improved compatibility between the silicone and polyolefin phases therein.
The present invention addresses the problem of providing formulations having improved sensory feel, while retaining other desired characteristics including spreadability and non-tacky feel on skin, by including silicone modified polyolefins which comprise a functionalized polyolefin and a functionalized silicone polymer. The silicone modified polyolefins can be swelled or dissolved in a carrier fluid to produce formulations having a soft, silky, and smooth feel and are easily spreadable and non-tacky on skin. It is believed that the silicone modified polyolefins may be used in many surface treatments where soft touch sensory characteristics are favored, including personal care, coatings, fabric care, and leather treatments.